As user requirements and technologies rapidly develop, the 5th generation mobile communications (5G for short) system or a new radio access technology (NR) are upcoming. The 5G system or an NR system can provide a transmission rate higher than that of a Long Term Evolution (LTE for short) network, and a highest theoretical transmission rate of the 5G system or the NR system can reach tens of gigabytes (Gb for short) per second. To increase the data transmission rate, the 5G system provides a multi-connectivity transmission method, that is, a terminal may access both the LTE network and the 5G system, and data of the terminal is transmitted by using both a base station of the LTE network and a base station of the 5G system. However, in an existing multi-connectivity solution, a data splitting anchor is in the LTE network. That is, the base station of the LTE network is a master base station, a base station of an NR network is a secondary base station, the master base station splits some data and transmits the data to the terminal by using the secondary base station, and the data is basically transmitted by using the LTE network. Compared with data transmission only on the LTE network, the existing multi-connectivity solution can also increase the data transmission rate, but cannot make use of an advantage of the data transmission rate of the 5G system.
Currently, two major researches of an LTE-NR multi-connectivity technology (LTE-NR tight interworking) are discussed in a standard. One research is radio resource control (RRC) diversity that is referred to as RRC diversity. The other research is directly generating an RRC message by a new radio access technology base station or a 5G base station (NR gNB) when the new radio access technology base station or the 5G base station serves as a secondary base station, and transmitting the RRC message to a terminal via an NR air interface, and this is referred to as a direct RRC message (direct RRC message).
FIG. 1 and FIG. 2 are schematic architectural diagrams of an LTE-NR multi-connectivity technology network in the prior art. The LTE-NR multi-connectivity technology network includes an LTE core network (EPC, E-UTRAN packet core), a new core network (NGC, NG-core), an LTE base station (eNB), and a new radio access technology base station (NR gNB). The new radio access technology may be 5G If an anchor base station is the LTE eNB, a corresponding secondary base station is the NR gNB. Correspondingly, if an anchor base station is the NR gNB, a corresponding secondary base station is the LTE eNB.
If the LTE eNB is an anchor base station, a protocol stack structure is shown in FIG. 3, and supports 3C and 1A. As shown in FIG. 1, for the 3C (split bearer), the LTE eNB is used as an anchor, data is split from a Packet Data Convergence Protocol (PDCP) layer to the gNB, and both a control plane (CP) and a user plane (UP) are on the LTE eNB; and for the 1A (SCG bearer), a control plane is on the LTE eNB, and a user plane is between the EPC and the gNB.
Assuming that the NR gNB is an anchor base station, a network architecture is shown in FIG. 2, and a protocol stack structure is shown in FIG. 4.
The LTE-NR multi-connectivity technology (LTE-NR tight interworking/LTE-NR DC) is as follows: A terminal performs access via LTE, a control plane is reserved in LTE, and then a user plane (UP) uses both LTE and 5G new radio in a manner similar to LTE DC (dual-connectivity), that is, the user plane is anchored at an LTE Packet Data Convergence Protocol (PDCP) layer to split data per data packet or bearer. Similarly, a terminal may alternatively perform access by using 5G, a control plane is reserved in 5G, and a user plane is anchored at a 5G PDCP layer in a manner similar to LTE DC to split data.
To meet an ultra-reliable and low latency communications (URLLC) service requirement, and to improve RRC message transmission reliability in an LTE-NR multi-connectivity scenario, if the anchor base station is the LTE eNB, an RRC message generated by the anchor base station (MeNB) may be separately transmitted to a terminal via an LTE air interface and an NR air interface. When the RRC message is transmitted to the terminal via the NR air interface, the RRC message needs to be transmitted to the NR gNB via an interface between LTE and NR, and then is sent by the NR gNB to the terminal. After receiving the signaling message, an NR module of the terminal converges the signaling message to an LTE module for processing.
In the LTE-NR multi-connectivity scenario, NR may have its own RRC entity, and the RRC entity may directly create and send an RRC message to the terminal. That is, after an NR gNB is added for the LTE eNB to perform multi-stream convergence data transmission, if the NR gNB needs to modify a configuration, the NR gNB directly generates an RRC configuration message, and sends the RRC configuration message to the terminal via the NR air interface.
In the case of two technologies, as NR has its own RRC entity and can send a direct RRC message, and NR supports RRC diversity, there is currently no technical solution of how to transmit an RRC message of the NR air interface and how a receive end identifies the RRC message.